System and method for coordination of wireless maintenance channel power control

ABSTRACT

In a wireless communication system, there are several wireless channels used for communication between users and a base station. Channel characteristics may be defined by whether a channel is carrying traffic data and the timing of the channel transmissions with respect to channels not carrying traffic data. Different power levels between channels carrying traffic data or not may be defined and individual power levels of each channel may be amended based on individual power level command responses.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/615,848 filed on Sep. 14, 2012, which is a divisional of U.S. patentapplication Ser. No. 12/938,864 filed on Nov. 3, 2010, which is adivisional of U.S. patent application Ser. No. 10/170,015, filed on Jun.11, 2002, which claims the benefit of U.S. Provisional Application No.60/297,839 filed on Jun. 13, 2001, which is incorporated by reference asif fully set forth.

BACKGROUND

In a wireless communication system, a number of radio channels provide aconnection between users and a central location, such as a base stationor access point. In such a system, the wireless channels are a scarceresource which must typically be shared. In a Code Division MultipleAccess (CDMA) system, a number of different channels can be transmittedon a single radio frequency carrier by applying different codes to eachsignal. However, even in a CDMA system, demand for access to channels isso great that the base station must allocate and switch the channelsamong multiple users.

Often, a wireless user may be switched on, but not actively sending orreceiving data. Accordingly, wireless users may be in an “active” mode,and currently allocated a wireless data traffic channel for sending orreceiving data, or in an “idle” mode, and not currently sending orreceiving data. An idle user may, for example, have just sent orreceived a data traffic transmission and is therefore deemed likely tosoon request a data traffic channel for further transmissions. Amaintenance message may therefore be employed to maintain a user in asynchronized but idle state to facilitate allocation of a wirelesstraffic channel when needed. When a user requests a channel, the idlestate allows the user to be allocated a wireless traffic channel morequickly than for a user who was not being maintained in a synchronizedidle state. For more information concerning one way to implement asystem, please refer to U.S. Pat. No. 6,222,832, entitled “FastAcquisition of Traffic Channels for a Highly Variable Data Rate ReverseLink of a CDMA Wireless Communication System,” assigned to TantivyCommunications, Inc., assignee of the present application.

A number of users, therefore, may be maintained in an idle state througha periodic sequence of maintenance messages. In the idle state, themaintenance messages typically provide time tracking and power control,and do not require phase reference information employed when in theactive state. Time tracking and power control signaling requires lesspower than the maintenance messages sent during active data payloadtransmission. The maintenance messages, however, are typically sent at asimilar power level during both the idle and active states. Accordingly,the maintenance messages can increase interference and battery powerdrain during the idle state.

SUMMARY

In a wireless communications system, synchronization maintenancemessages are often employed to maintain a user in an idle state byproviding time tracking and power control. According to the presentinvention, a method for controlling the power level of a wirelessmessage which defines a maintenance channel operable to transmitsynchronization maintenance messages (synchronization messages) includesdetermining the presence of data to be transmitted from a wirelessaccess terminal to a base station. The power level of thesynchronization message sent from the access terminal via themaintenance channel is adjusted depending on the presence of data to besent. Synchronization messages for idle state synchronization providetime tracking and power control signaling, while synchronizationmessages corresponding to active data traffic transmissions also providephase reference for the data traffic transmissions. The synchronizationmessages corresponding to the idle state employ a lower power level thanthe active state transmissions which employ a higher power level.

In this manner, the system monitors the presence of data and controlsthe power level accordingly such that synchronization messages are sentat a lower power level in the idle state, when no data is present,thereby reducing power consumption and interference.

More specifically, a data transmission state is maintained at thewireless access terminal to indicate the presence of data to transmitvia a data traffic channel on a reverse link. The power level of asynchronization message is computed in response to the data transmissionstate. Target power levels are maintained for the idle state and theactive state. The synchronization messages are sent from the accessterminal to the base station at the corresponding power level. Powercontrol messages (return messages) sent in response from the basestation manage the power level towards the applicable target powerlevel.

A maintenance channel connection is maintained for transmission of thesynchronization messages. The maintenance channel typically transmitsunmodulated, or pilot, signals for maintaining synchronization. Sincethe maintenance channel is not a dedicated data traffic channel, aplurality of access terminals may be maintained over a singlemaintenance channel using a plurality of time slots.

The synchronization messages are typically sent at predeterminedintervals from each of the access terminals. In the idle state,synchronization messages are sent according to a gating rate. In theactive state, synchronization messages are sent continuously in order tomaintain a phase reference for a corresponding data traffictransmission. Return power control messages are sent in response to thesynchronization messages including power control and time trackinginformation according to a power control group.

The access terminal determines the data transmission state, either ON(active) or OFF (idle), and adjusts transmission power accordingly. Thebase station, in turn, determines the data transmission state andadjusts information in the return messages accordingly to control thepower level toward one of an active power control target and an idlepower control target. Further, the access terminal disregards returnmessages for a predetermined interval after a change in the datatransmission state to allow for recognition and adjustment of the datatransmission state change by the base station. The target power level isdetermined by the base station using factors including the receivedsignal strength, received signal quality, Carrier-to-Interference (C/I)ratio, and the Signal to Noise Ratio (SNR).

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIGS. 1a-1c are diagrams of prior art maintenance messages for awireless maintenance channel;

FIG. 2 is a diagram of a wireless communication system employing theinvention as defined by the present claims;

FIG. 3 shows the forward and reverse links between a wireless accessterminal and a base station for message transmission;

FIG. 4 is a diagram of wireless synchronization messages as defined bythe present claims;

FIG. 5 shows idle and active power levels;

FIG. 6 is a flowchart of message transmission;

FIG. 7 is a flowchart of a power control loop for managing transmissionpower according to the target power levels; and

FIG. 8 is a message transmission sequence diagram showing the transitionbetween data transmission states.

DETAILED DESCRIPTION

A description of preferred embodiments of the invention follows.

The wireless system as disclosed herein employs a reverse linkmaintenance channel for maintaining synchronization and other stateinformation for a plurality of subscriber access terminals. Thesubscriber access terminals support users by providing a wireless linkto a base station processor for communication with a data network suchas the Internet. The wireless link is provided by one or more wirelesschannels managed by the base station. The wireless channels aredynamically allocated by the base station among the multiple accessterminals depending on data transmission needs, and typically do notremain dedicated to a single user.

A maintenance channel, therefore, is employed to maintain an accessterminal in synchronization with the base station when it is notactively sending data. Such a maintenance channel is capable ofmaintaining a plurality of access terminals at the same time. Thissynchronization allows an access terminal to be allocated a data trafficchannel more readily when needed for data traffic transmission than thatwhich would be required to set up and tear down a reverse link wirelesschannel each time the access terminal was to send or receive datamessages.

FIGS. 1a-1c show a diagram of several different types of maintenancemessages used in the prior art. Referring to FIGS. 1a-1c , the powerlevel of the maintenance messages are shown for three different gatingrates—1, ½ and ¼, respectively. When an access terminal is in an idlestate and not actively sending or receiving data, as shown by the “dataoff/gated” period 10, a maintenance message is sent to maintain timetracking and power control. The idle state message need not becontinuous. It is sent in a time slotted or gated manner according to agating rate 14 a-14 c, for the duration of a 20 ms power control group18. As shown in FIGS. 1a-1c , respectively, several different gatingrates have been used. During a “data on” period 12, the maintenancemessage is sent continuously, as shown by the continuous transmissions16 a-16 c. However, during each power control group 18 gated messagesare sent at the same power level, as shown by the power level on axis20. As the maintenance messages sent during the data off period 10 areemployed for time tracking and power control, they need not be sent atthe same power level afforded to the maintenance messages sent duringthe data on period 12, which are used also for phase reference for acorresponding data traffic channel.

FIG. 2 is a diagram of a wireless communication system 22 employing theinvention as defined by the present claims A plurality of subscriberterminals 24 (access terminals) are in wireless communication with abase station processor 26 (base station) via wireless links 30. The basestation 26 is also connected to the Internet 28 via a wired link 32 toact as a gateway for the access terminals 24. The access terminals 24provide wireless Internet access to customer premises equipment (CPE) 32generally, such as desktop PCs 32 a, 32 c, personal digital assistants(PDAs) 32 b, wireless phones 32 d, and other devices such as laptops,pagers, and automotive telematics devices, not shown. It should be notedthat the wireless functionality provided by the access terminal 24 maybe in a stand alone device such as a subscriber access unit or embeddedin the CPE 32 unit. In either case the CPE is operable to communicatewith the Internet 28 via the wireless link 30 and the base station 26.

FIG. 3 shows forward and reverse links between an access terminal and abase station for message transmission. Referring to FIGS. 2 and 3, thewireless links include both a forward link 34 and a reverse link 36 topermit duplex communication. The forward link supports wireless channelsfor carrying messages from the base station 26 to the access terminal24, and the reverse link 36 supports wireless channels for carryingmessages from the access terminal 24 to the base station.

Each of the access terminals 24 periodically sends a synchronizationmessage via the reverse link 36 to the base station 26. Thesynchronization message includes time tracking and power controlinformation sufficient to maintain the access terminal in at least anidle state, and therefore synchronized with the base station 26. Thebase station responds with a power control message via the forward link34. The power control message includes power control commands to directthe power level of subsequent messages to allow the access terminal 24to remain synchronized with the base station 26. The power level isdetermined by a power level controller 38 at the base station forcomputing a target power level for both the idle and active datatransmission states.

The forward 34 and reverse 36 links further comprise data trafficchannels for transmitting wireless messages having a data payload. Thedata traffic channels are allocated by the base station 26 to an accessterminal 24 when the access terminal 24 is to send or receive data. Adata transmission state, described further below, is indicative ofwhether the access terminal 24 is allocated a data traffic channel. Whenthe data transmission state is active, the synchronization messagesprovide a phase reference for the messages transmitted on the datatraffic channels, in addition to time tracking and power control.

Synchronization messages employed for only for time trackingsynchronization and power control, however, do not require as much poweras the synchronization messages used to provide phase reference duringthe active data transmission state. Therefore, according to the presentinvention, synchronization messages are sent at a reduced power level inthe idle data transmission state. Additional power is provided for thesynchronization message when it is also employed for phase reference.Accordingly, the synchronization messages are sent at a lower powerlevel in the idle data transmission state than in the active datatransmission state.

FIG. 4 is a power level diagram for the invention. Referring to FIGS. 4and 2, during an idle (OFF) data transmission state 40, thesynchronization messages are sent in a gated manner according to agating rate. A gating rate of ¼ is shown as exemplary; other gatingrates could be employed. The power level of the message is shown by theaxis 44. When the data transmission state transitions to active (ON) 42,the power level 44 is increased to allow the synchronization messages tobe employed for phase reference as well.

As indicated above, synchronization messages are transmitted at one oftwo power levels. The power level is managed by the base station 26 andtransmitted to the access terminal 24 via the power control messages.The access terminal 24 responds by transmitting at the power levelproscribed by the base station. The base station 26 computes a targetpower level, described further below, indicative of the power level atwhich the access terminal should transmit. Typically, the power level isexpressed as effective radiated power in decibels (dB), however, othermetrics could be employed. The base station, therefore, maintains targetpower levels for each of the data transmission states. An active targetpower level corresponds to the ON data transmission state and an idletarget power level corresponds to the OFF data transmission state.

FIG. 5 shows idle and active power levels in more detail. Periods 46correspond to OFF data transmission state, and period 48 corresponds toON data transmission state. The power level 44 indicates the power levelof the synchronization messages. The idle target power level, shown bydotted line 50, indicates the power level at which synchronizationmessages should be sent during OFF data transmission state. The activetarget power level, shown by dotted line 52, indicates the power levelat which synchronization messages should be sent during ON datatransmission state.

The access terminal 24 maintains the idle and active target power levels50, 52. The base station 26 manages the transmission power of themessages sent by the access terminal 24 by the power control messages,which are sent by the base station 26 to adjust the idle and activetarget power levels 50, 52. The access terminal 24 determines when thedata transmission state changes and toggles between the active and idletransmission power levels, and transmits according to the correspondingpower level. The base station 26 determines a change in the datatransmission state, described further below, and adjusts the powercontrol messages accordingly.

While the data transmission state affects whether transmission occurs atthe active or idle power level, other factors affect the perceived powerlevel as well. The distance from the access terminal 24 to the basestation 26, intervening objects, interference from other sources, andother factors all can affect the perceived power level of the wirelessmessages. Accordingly, the base station 26 examines the received signalquality, indicative of the power level of a received message, andcomputes the power control message accordingly. If a message from theaccess terminal 24 is being received at too low a perceived power level,the base station will transmit power control messages indicative of ahigher power level at which to transmit. Similarly, if a message isreceived from the access terminal 24 at too high a perceived powerlevel, the base station will transmit power control messages indicativeof a lower power level at which to transmit. The base station,therefore, manages the power level of messages transmitted from theaccess terminal by focusing on a target power level.

Accordingly, when the access terminal 24 changes data transmissionstates, the base station will receive messages at a different powerlevel. The base station determines that the change in power level is dueto a change in data transmission state, and not to other factorsdescribed above, and continues to compute the idle and active powerlevels accordingly. Further, as the power control messages are typicallysent according to power control groups of 16 every 20 ms, or every 1.25ms, the base station may not determine the data transmission state untilseveral power control message cycles. Accordingly, the access terminal24 may disregard power control messages for a predetermined period aftertoggling data transmission states. The access terminal, therefore, maytoggle between the active and idle power levels without the base station26 countering with power control messages which would otherwiseundermine the transmission of reduced power synchronization messages.

FIG. 6 is a flowchart of synchronization message transmission accordingto a particular embodiment of the invention. Referring also to FIG. 2again, an access terminal 24 determines if there is data ready to betransmitted on a traffic channel, as depicted at step 100. A check isperformed to set or maintain the data transmission state accordingly, asshown at step 102. If there is no data waiting to be transmitted, theaccess terminal 24 enters or maintains the data transmission state ofidle, as depicted at step 104. If there is data waiting to betransmitted, the access terminal 24 enters or maintains the datatransmission state of active, as shown at step 106.

In the idle data transmission state, the access terminal sets 24 thetransmission power level at the idle target power level, as disclosed atstep 108. The access terminal then determines the gating rate of theidle state message, as determined at step 110. In the idle mode, themessage is sent in a gated, or periodic manner, such as ¼, ½, or 1. Thegating rate results in a periodic delay, prior to sending the nextsynchronization message.

In the active data transmission state, the access terminal 24 set setsthe transmission power level at the active target power level, as shownat step 112. The access terminal then sets the message as continuous,with no gating, as shown at step 114.

The access terminal 24 then sends a synchronization message to a basestation 26, as depicted at step 116. The base station 26 receives thesynchronization message, as disclosed at step 118, and determines thedata transmission state, as shown at step 120.

Determination of the data transmission state is discussed further belowwith respect to FIG. 7. A check is performed to examine the determineddata transmission state, as disclosed at step 122. If the datatransmission state is idle, then the base station computes or maintainsa new idle target power level, as depicted at step 124. If the datatransmission state is active, then the base station computes a newactive target power level, as shown at step 126. The base station 26then sends a power control message indicative of the computed targetpower level to the access terminal 24, as shown at step 128.

The access terminal 24 receives the power control message, including thenew target power level, as shown at step 130. The access terminal 24then determines when to send the next synchronization message, dependingon gating rate, as depicted at step 132, and control reverts to step100.

In a gated manner, the access terminal 24 periodically sends thesynchronization message depending on the gating rate. Accordingly, theaccess terminal 24 may wait for one or more power control groupintervals of 1.25 ms each to elapse before sending the nextsynchronization message, as shown above in FIG. 4. Alternatively, in theactive data transmission state, the synchronization messages are sent ina continuous manner, also as shown in FIG. 4.

FIG. 7 is a flowchart of a power control loop for managing transmissionpower according to the determined target power levels. Referring to FIG.2 as well, the determination of the data transmission state is shown.The base station 26 receives the synchronization message from the accessterminal 24, as shown at step 150. The base station determines whichmetric to employ to determine the data transmission state at the accessterminal 24, as shown at step 152. As the access terminal toggles thedata transmission state between active and idle, the base stationdetermines the current data transmission state from the synchronizationmessages as they are received. The base station 26 then attempts to setthe target power level reflected in the power control messagesaccordingly.

The base station 26 examines the received quality level of thesynchronization message to determine the power level at which it wassent, and hence the data transmission state of either idle or active, asdepicted at step 154. As indicated above, the access terminal 24transmits at one of the idle or active power levels depending on thedata transmission state. However, the base station 26 attempts to adjustthe target power level such that access terminal transmissions arereceived uniformly at the base station 26. Accordingly, the base station26 determines a transmission quality based on a link quality metric.Since the received quality level may be affected by other factors inaddition to transmission power employed by the access terminal 24, suchas noise, interference, and reflection, other metrics may be used toassess received signal quality and determine the sending power level.

Alternatively, the base station may receive a separate data transmissionstate indication according to a periodic interval, as shown at step 156.Such a predetermined interval may be according to the gating rate, oraccording to a predetermined interval agreed to by the base station andthe access terminal, as described in U.S. patent application No.60/346,527, entitled “Coordination of Pilot Power Level Based onPeriodic Intervals”, filed Jan. 8, 2002 and incorporated herein byreference.

The base station 26 may also receive the data transmission stateencapsulated in the synchronization message, as shown at step 158. Adetectable signal encapsulated in the synchronization message isdetected by the base station, and employed to set the data transmissionstate, and the associated target power control level, at the basestation 26 accordingly.

In another embodiment, the base station employs a MAC (media accesscontrol) state to determine the data transmission state, as disclosed atstep 160. The MAC state transitions are indicated by a signal in thesynchronization message. The base station detects the MAC state change,as described in U.S. patent application No. 60/346,525, entitled“Coordination of Pilot Power Level Based on MAC State”, filed Jan. 8,2002, incorporated herein by reference, and sets the data transmissionstate accordingly.

In alternate embodiments, other methods may be employed to detect achange in data transmission state at the base station 26. The basestation 26 therefore, determines the data transmission state from thesynchronization message, and sets its own indicator accordingly, asdepicted at step 162. The indicator is employed in determining thetarget power level to set in the power control message, as disclosed atstep 164. Other factors which affect the target power level include theC/I (Carrier to Interference) ratio or the SNR (Signal-to-Noise ratio),in addition to the received power level. Further discussion of powercontrol messages and power control groups is disclosed in copending U.S.patent application Ser. No. 09/999,172, filed Nov. 30, 2001, entitled“Antenna Control System and Method”, incorporated herein by reference.Once the target power level is determined, corresponding to a datatransmission state of idle or active at the access terminal 24, controlresumes at step 120 in FIG. 6.

FIG. 8 is a message transmission sequence diagram showing a transitionbetween data transmission states. A timing diagram 60 of a maintenancechannel is shown. A plurality of synchronization messages 62 a-62 g aresent from an access terminal 24 to a base station 26. A complementaryplurality of power control messages 64 a-64 g are sent from the basestation 26 to the access terminal 24. The data transmission state (DT)at the access terminal 24 is shown by the hatched bars 66, and the DTstate at the base station are shown by the hatched bars 68. At aninitial time T=0, the DT state 66 at the access terminal 24 is idle (I),as shown by hatched area 70, and the DT state at the base station 26 isalso idle for this user, as shown by hatched area 72. Thesynchronization message 62 a is sent at a power level (PL) correspondingto the idle power level, and is sent in a gated (G=Y) manner since onlysynchronization information need be transmitted. The base station 26responds with a power control message 64 a indicating power control (PC)is to be maintained at the Idle level. The access terminal 24 receivesthe power control message 64 a to maintain the Idle power level. Thenext synchronization message 62 b is sent, also PL=I and G=Y, and thebase station 26 responds with power control message 64 b, PC=I. A seriesof idle state (DT=I) messages may continue, described above with respectto FIGS. 6 and 7, as shown by dotted line 90.

The access terminal 24 detects data present to be transmitted on a datatraffic channel (not shown), and changes the DT state 66 to active (ON),as shown by hatched area 74. The synchronization message 62 c is nowtransmitted at a power level of “A” (Active) and is sent in a constant(non-gated) manner G=N. Upon receiving the synchronization message, thebase station 26 determines that there is data traffic present, andtoggles the DT state 68 to A, as shown by hatched bar 76. The basestation responds with power control message 64 c, indicating powercontrol is to target the active level (PC=A). The synchronizationmessage 62 d is transmitted at PL=A and G=N, and a power control message64 d is received for PC=A. A series of active state (DT=A) messages maycontinue, as described above with respect to FIGS. 6 and 7, as shown bydotted line 92. Synchronization message 62 e is then sent, whichcorresponds to the last active state message in this sequence 62 c-62 e.

Power control message 64 e is sent, and the access terminal 24determines that there is currently no more data to transmit.Accordingly, the DT state 66 toggles to “I,” (Idle) as shown by hatchedarea 78, and synchronization message 62 f is sent, at PL=I and G=Y. Thebase station 26 receives the message 62 f, determines that there is nodata presently being transmitted, and toggles the DT state 68 to “I,” asshown by hatched area 80. Power control message 64 f is sent inresponse, at PC=I. Idle mode messages 62 g and 64 g follow in order, tocontinue the synchronization maintenance cycle, until the next active DTstate.

The embodiment described above includes two power control levels of idleand active as illustrative. Multiple power level thresholds could bemaintained between a access terminal 24 and a base station 26.Accordingly, the invention as described herein may be employed toprovide multiple levels of standby or idle status, depending on thelevel of signaling capability employed at each level, for the purpose ofminimizing interference and maintaining synchronization between anaccess terminal 24 and a base station 26.

Those skilled in the art should readily appreciate that the system andmethods for synchronization message power control as defined herein aredeliverable to a wireless device in many forms, including but notlimited to a) information permanently stored on non-writeable storagemedia such as ROM devices, b) information alterably stored on writeablestorage media such as floppy disks, magnetic tapes, CDs, RAM devices,and other magnetic and optical media, or c) information conveyed to acomputer through communication media, for example using basebandsignaling or broadband signaling techniques, as in an electronic networksuch as the Internet or telephone modem lines. The operations andmethods may be implemented in a software executable by a processor or asa set of instructions embedded in a carrier wave. Alternatively, theoperations and methods may be embodied in whole or in part usinghardware components, such as Application Specific Integrated Circuits(ASICs), state machines, controllers or other hardware components ordevices, or a combination of hardware, software, and firmwarecomponents.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

What is claimed is:
 1. A subscriber unit comprising: an antenna; acircuit operatively coupled to the antenna, the circuit configured totransmit traffic data to a network on a first type of channel andcontrol information to the network on a second type of channel that doesnot carry traffic data, wherein the control information is transmittedon the second type of channel in at least one second time period betweena first time period in which traffic data is being transmitted on thefirst type of channel and a third time period in which traffic data isbeing transmitted on the first type of channel; wherein the circuit isfurther configured to transmit a quality level indicator on the secondtype of channel; wherein the circuit is further configured to receivefirst power commands for the first type of channel from the network andsecond power commands for the second type of channel from the network;and wherein the circuit is further configured to set a transmissionpower level for the first type of channel in response to the first powercommands and not the second power commands and set a transmission powerlevel for the second type of channel in response to the second powercommands and not the first power commands.
 2. The subscriber unit ofclaim 1, wherein the circuit is further configured to transmit anindication on the second type of channel that the subscriber unit hastraffic data to send on the first type of channel.
 3. The subscriberunit of claim 1, wherein the second type of channel is a maintenancechannel.
 4. The subscriber unit of claim 1, wherein the second type ofchannel is not transmitted continuously.
 5. The subscriber unit of claim1, wherein the transmission power level of the first type of channelafter transmission of the second type of channel is based on first powercommands received before and after transmission of the second type ofchannel.
 6. The subscriber unit of claim 1, wherein the at least onesecond time period comprises a continuous transmission interval.
 7. Thesubscriber unit of claim 1, wherein the at least one second time periodcomprises multiple transmission intervals.
 8. The subscriber unit ofclaim 1, wherein the at least one second time period does not occurduring the first time period or the third time period.
 9. The subscriberunit of claim 1, wherein the first type of channel is a data trafficchannel.
 10. A method comprising: transmitting, by a subscriber unit,traffic data to a network on a first type of channel and controlinformation to the network on a second type of channel that does notcarry traffic data, wherein the control information is transmitted onthe second type of channel in at least one second time period between afirst time period in which traffic data is being transmitted on thefirst type of channel and a third time period in which traffic data isbeing transmitted on the first type of channel; transmitting, by thesubscriber unit, a quality level indicator on the second type ofchannel; receiving, by the subscriber unit, first power commands for thefirst type of channel from the network and second power commands for thesecond type of channel from the network; and setting, by the subscriberunit, a transmission power level for the first type of channel inresponse to the first power commands and not the second power commandsand a transmission power level for the second type of channel inresponse to the second power commands and not the first power commands.11. The method of claim 10, further comprising: transmitting, by thesubscriber unit, an indication on the second type of channel that thesubscriber unit has traffic data to send on the first type of channel.12. The method of claim 10, wherein the second type of channel is amaintenance channel.
 13. The method of claim 10, wherein the second typeof channel is not transmitted continuously.
 14. The method of claim 10,wherein the transmission power level of the first type of channel aftertransmission of the second type of channel is based on first powercommands received before and after transmission of the second type ofchannel.
 15. The method of claim 10, wherein the at least one secondtime period comprises a continuous transmission interval.
 16. The methodof claim 10, wherein the at least one second time period comprisesmultiple transmission intervals.
 17. The method of claim 10, wherein theat least one second time period does not occur during the first timeperiod or the third time period.
 18. The method of claim 10, wherein thefirst type of channel is a data traffic channel.
 19. A network devicecomprising: an antenna, a circuit operatively coupled to the antenna,the circuit configured to receive traffic data from a subscriber unit ona first type of channel and control information from the subscriber uniton a second type of channel that does not carry traffic data, whereinthe control information on the second type of channel is received in atleast one second time period between a first time period in whichtraffic data is being received on the first type of channel and a thirdtime period in which traffic data is being received on the first type ofchannel; wherein the circuit is further configured to receive a qualitylevel indicator on the second type of channel; wherein the circuit isfurther configured to derive first power commands for the first type ofchannel and second power commands for the second type of channel; andwherein the circuit is further configured to transmit the first powercommands and the second power commands to the subscriber unit.
 20. Thenetwork device of claim 19, further comprising: wherein the circuit isfurther configured to receive an indication on the second type ofchannel that the subscriber unit has traffic data to send on the firsttype of channel.
 21. The network device of claim 19, wherein the secondtype of channel is a maintenance channel.
 22. The network device ofclaim 19, wherein the second type of channel is not receivedcontinuously.
 23. The network device of claim 19, wherein a transmissionpower level of the first type of channel after transmission of thesecond type of channel is based on first power commands received beforeand after transmission of the second type of channel.
 24. The networkdevice of claim 19, wherein the at least one second time periodcomprises a continuous transmission interval.
 25. The network device ofclaim 19, wherein the at least one second time period comprises multipletransmission intervals.
 26. The network device of claim 19, wherein theat least one second time period does not occur during the first timeperiod or the third time period.
 27. The network device of claim 19,wherein the first type of channel is a data traffic channel.